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Allergic colic rising, even in breast-fed infants. (Mucus in Stool is Telltale Sign).

MIAMI -- Pediatricians who have been around long enough to have a few gray hairs swear they're seeing allergic colitis a lot more frequently then they used to.

"I've been a pediatric gastroenterologist for almost 20 years, and I get the impression that the incidence of allergic colitis is going up." What's most surprising is that it's occurring increasingly among infants who are breastfed only, Dr. John Thompson noted at a pediatric update sponsored by the University of Miami.

"I don't know if there are data to support this, and I can't think of a mechanism of what would cause it," but this is becoming very common, said Dr. Thompson of the university, whose observation was shared by many in the roomful of pediatricians.

The typical patient is the 1- to 3-month-old infant who is crying inconsolably, has nonbilious vomiting with stools that are pasty and streaked with blood and mucus.

These are the babies who have unremarkable birth histories and normal growth patterns; they passed meconium in the first 24 hours of life, and their physical exams are normal, without any anorectal fissures to explain the passing of blood.

The telltale sign is the mucus in the stool because where there's mucus, there's inflammation and probably colitis, Dr. Thompson said. The colitis can be due to a bacterial infection such as Salmonella, Shigella, Campylobacter, or Clostridium difficile. Hirschsprung's disease is another possibility because it can present as colitis.

But the most probable explanation is allergic colitis.

Malrotation is in the differential diagnosis, but it's one that would be "pretty unlikely." Still, when an infant is spitting up all the time, "you have to ask [parents] about bile. And if you decide not to do an upper GI on these babies, you have to make sure the parents understand that if they ever spit up bile, [even just once], they have to get an upper GI right away to rule out a malrotation," he said. Then select a radiologist who knows what he or she is doing in looking for the ligament of Treitz is key.

Once a child is a few months old, it's a little late for necrotizing enterocolitis, but it still should be considered as part of the differential. If there's any history of heart disease or a perinatal problem, "you would be a little bit more worried" about necrotizing enterocolitis because under such circumstances it could show up a little bit later.

In working up suspected colitis, at the very least Dr. Thompson recommended getting a Hemoccult test, an abdominal radiograph (kidney, ureter, and bladder), and culturing the stool for C. difficile. "I personally don't do sigmoidoscopies or rectal biopsies on these kids," he added.

The mechanism that causes allergic colitis in breast-fed children is not well understood. One hypothesis is that mothers who eat dairy pass milk protein antigens into their breast milk. Radioimmunoassay studies demonstrate this phenomenon by showing that "you can actually see cows' milk antigens in mother's milk." However, the theory falls short in explaining how the peptide is absorbed and deposited into the breast milk. Another explanation is that cytokines in mother's milk are mediating the allergy.

Because dietary changes are the primary management strategy, when an infant with a history of only breast-feeding develops allergic colitis, the issue of whether to stop breast-feeding has to be determined. In most cases, since the bleeding tends to be minimal, the best strategy is to continue breast-feeding because the child is going to outgrow the allergy.

Children are prone to food allergy because their gut epithelium tends to be relatively leaky, so whole proteins cross it easily. As their gut matures, the epithelium gets tighter and the allergy almost always goes away, which is why nursing through these things is usually OK, he said.

But just to be safe, Dr. Thompson recommended getting serum albumen as well. "I don't think you can judge by looking at how much [blood and mucus] there is." These babies don't tend to lose that much blood, but they still can get sick, and serum albumen is a good marker. If there's a lot of inflammation, serum albumen is going to go down," he said.

If the child is on regular formula, switch to a hypoallergenic formula, such as Alimentum, Nutramigen, or Pregestimil. Alimentum has a little sugar, so it's sweeter and is probably the best tasting, but any of the three is worth trying, he said.

The one caveat is that some babies are going to have persistent allergy. The formulas are made by taking cows' milk casein and incubating it with porcine trypsin, which creates peptides about three to eight amino acids long. Some infants are sensitive to even these short peptides.

If signs of allergy persist, try switching among the hypoallergenic formulas. As a last resort, there are amino acid-based formulas, such as Neocate, which is the only one on the market for infants under 12 months of age, but it's very expensive.

Whatever dietary change is tried, it should only take 3-4 days for the visual evidence of mucus and blood to resolve, although the stool may remain Hemoccult positive. If it takes more time, chances are "your intervention hasn't done the trick," he said. The good news is that most kids outgrow their food allergies and can be rechallenged within 6-9 months.

Food allergy frequently goes hand in hand with gastric reflux. But an upper GI is not recommended unless there's an episode of bile suggesting a malrotation.

Instead, giving the child 1 mL of Maalox is often diagnostic. If the problem is reflux, they should get better in about 5 minutes. Then treat them empirically with an H2 blocker. Dr. Thompson said not to hesitate in treating "refluxers" with either Pepcid or Zantac because many will develop a feeding aversion later on if their discomfort is not addressed early. The Zantac dosage is anywhere from 4 to 6 mg/kg daily. And the dose should be divided three times daily, rather than twice daily, because of the half-life.

Long-term treatment with Maalox is not recommended because there's aluminium in it, he said.
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Author:DeMott, Kathryn
Publication:Pediatric News
Article Type:Brief Article
Geographic Code:1USA
Date:Aug 1, 2002
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